Light Pollution Effects of Illuminance on Yellowish Green Forsterite Color under CIE Standard Light Source D65

Abstract

Ecological light pollution is the effect of artificial light on individual organisms and on the structure of ecosystems as a whole. This research investigates the light pollution effects of illuminance and color genesis in forsterite. The color of 11 forsterite was measured using colorimeter under D65 with different illuminance levels based on CIE1976 L*a*b* uniform color space system. With illuminance increasing from 500lx to 3000lx, the ecological impact of light pollution soars but the hue angle keeps reducing until 2500lx before stable, while the chroma reaches its peak at 2500lx. It suggests Hunt effect, Stevens effect as well as Bezold-Brucke hue shift also fits in forsterite and the illuminance 2500lx performs best for displaying. For further feasibility, six Fisher linear discriminant functions were produced for color data acquired under six levels of illuminance, respectively. The accuracy proves to be up to 80.3%. And a notable linear relation was found between chroma and colorimetry index b*(R2 = 0.98271) instead of a*, which indicates that light pollution effects of illuminance on forsterite decreases unded CIE standard light source. Combined with chemical compositions, it shows that Fe2+ in forsterite is the root of yellow hue. The effects of illuminance are caused by the spectral power distribution of D65 and the selective absorption of Fe2+ and should be considered during color evaluation of forsterite.